diff options
| author | Eric Dumazet <eric.dumazet@gmail.com> | 2011-08-09 12:15:58 +0400 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2011-08-12 13:55:28 +0400 |
| commit | cd28ca0a3dd17c68d24b839602a0e6268ad28b5d (patch) | |
| tree | 3e77945743e2c74c36b6942ad5bfe46a07eb9caa /net | |
| parent | 68c3e5a7b91513010d2536e4bcd7bdd54d0e6acf (diff) | |
| download | linux-cd28ca0a3dd17c68d24b839602a0e6268ad28b5d.tar.xz | |
neigh: reduce arp latency
Remove the artificial HZ latency on arp resolution.
Instead of firing a timer in one jiffy (up to 10 ms if HZ=100), lets
send the ARP message immediately.
Before patch :
# arp -d 192.168.20.108 ; ping -c 3 192.168.20.108
PING 192.168.20.108 (192.168.20.108) 56(84) bytes of data.
64 bytes from 192.168.20.108: icmp_seq=1 ttl=64 time=9.91 ms
64 bytes from 192.168.20.108: icmp_seq=2 ttl=64 time=0.065 ms
64 bytes from 192.168.20.108: icmp_seq=3 ttl=64 time=0.061 ms
After patch :
$ arp -d 192.168.20.108 ; ping -c 3 192.168.20.108
PING 192.168.20.108 (192.168.20.108) 56(84) bytes of data.
64 bytes from 192.168.20.108: icmp_seq=1 ttl=64 time=0.152 ms
64 bytes from 192.168.20.108: icmp_seq=2 ttl=64 time=0.064 ms
64 bytes from 192.168.20.108: icmp_seq=3 ttl=64 time=0.074 ms
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
| -rw-r--r-- | net/core/neighbour.c | 40 |
1 files changed, 26 insertions, 14 deletions
diff --git a/net/core/neighbour.c b/net/core/neighbour.c index 8fab9b0bb203..4002261f20d1 100644 --- a/net/core/neighbour.c +++ b/net/core/neighbour.c @@ -844,6 +844,19 @@ static void neigh_invalidate(struct neighbour *neigh) skb_queue_purge(&neigh->arp_queue); } +static void neigh_probe(struct neighbour *neigh) + __releases(neigh->lock) +{ + struct sk_buff *skb = skb_peek(&neigh->arp_queue); + /* keep skb alive even if arp_queue overflows */ + if (skb) + skb = skb_copy(skb, GFP_ATOMIC); + write_unlock(&neigh->lock); + neigh->ops->solicit(neigh, skb); + atomic_inc(&neigh->probes); + kfree_skb(skb); +} + /* Called when a timer expires for a neighbour entry. */ static void neigh_timer_handler(unsigned long arg) @@ -920,14 +933,7 @@ static void neigh_timer_handler(unsigned long arg) neigh_hold(neigh); } if (neigh->nud_state & (NUD_INCOMPLETE | NUD_PROBE)) { - struct sk_buff *skb = skb_peek(&neigh->arp_queue); - /* keep skb alive even if arp_queue overflows */ - if (skb) - skb = skb_copy(skb, GFP_ATOMIC); - write_unlock(&neigh->lock); - neigh->ops->solicit(neigh, skb); - atomic_inc(&neigh->probes); - kfree_skb(skb); + neigh_probe(neigh); } else { out: write_unlock(&neigh->lock); @@ -942,7 +948,7 @@ out: int __neigh_event_send(struct neighbour *neigh, struct sk_buff *skb) { int rc; - unsigned long now; + bool immediate_probe = false; write_lock_bh(&neigh->lock); @@ -950,14 +956,16 @@ int __neigh_event_send(struct neighbour *neigh, struct sk_buff *skb) if (neigh->nud_state & (NUD_CONNECTED | NUD_DELAY | NUD_PROBE)) goto out_unlock_bh; - now = jiffies; - if (!(neigh->nud_state & (NUD_STALE | NUD_INCOMPLETE))) { if (neigh->parms->mcast_probes + neigh->parms->app_probes) { + unsigned long next, now = jiffies; + atomic_set(&neigh->probes, neigh->parms->ucast_probes); neigh->nud_state = NUD_INCOMPLETE; - neigh->updated = jiffies; - neigh_add_timer(neigh, now + 1); + neigh->updated = now; + next = now + max(neigh->parms->retrans_time, HZ/2); + neigh_add_timer(neigh, next); + immediate_probe = true; } else { neigh->nud_state = NUD_FAILED; neigh->updated = jiffies; @@ -989,7 +997,11 @@ int __neigh_event_send(struct neighbour *neigh, struct sk_buff *skb) rc = 1; } out_unlock_bh: - write_unlock_bh(&neigh->lock); + if (immediate_probe) + neigh_probe(neigh); + else + write_unlock(&neigh->lock); + local_bh_enable(); return rc; } EXPORT_SYMBOL(__neigh_event_send); |